1. Field of the Invention
This invention relates to an image forming apparatus having composite modes, and more particularly, to an image forming apparatus having duplex and/or multiplex composite modes.
2. Description of the Related Art
Image forming apparatuses having a recycling automatic document (original) feeder (conveyor) (hereinafter termed an RDF) combined with the main body of the image forming apparatus, such as a copier or the like, are generally known. In such devices, a bundle of originals is set on an original mount (tray) and the originals are individually fed to an image reading position (exposing position) starting with the final page. The original, whose image has been read (exposed), is thereafter returned to the original mount.
In one copying mode a plurality of images are formed from each original using an RDF in a single-sided original--duplex image forming mode (simplex/duplex copy), in which respective images are formed on two surfaces of a recording medium (transfer paper or the like) from two single-sided originals. In that mode the image forming apparatus has (a) a "first image forming mode", wherein, there is a first recycling operation in which each original is recycled a plurality of times, an image is formed from every other original while the number of originals is counted, copies with formed images are stored in an intermediate tray, sheets of the recording medium are alternately fed for image formation from a recording-medium feeding unit and the intermediate tray in respective recycling operations from a second recycling operation up to a final recycling operation corresponding to the number of copies, and image formation is performed while feeding every other original from the intermediate tray in the final recycling operation, and (b) a "second image forming mode", in which a plurality of copies are formed from each original while performing only one recycling operation.
When a sheet jam has occurred "during a sheet-feeding operation from the intermediate tray" or "during an image forming mode", the following two types of recovering operations are provided.
a) A "first recovering operation", in which after returning to a predetertermined original in the first recycling operation, an image is formed from every other original, and formed images are stored in the intermediate tray. After returning to the predetermined original in the second recycling operation, sheets of the recording medium are alternately fed for image formation from the feeding unit and the intermediate tray in respective recycling operations from a second recycling operation up to a final recycling operation corresponding to the number of copies. In the final recycling operation, a recovering operation is performed while feeding every other original from the intermediate tray.
b) A "second recovering operation", in which after first returning to a predetermined original, a recovering operation is performed in the above-described second image forming mode.
Conventionally, irrespective of the number of copies and the number of originals, the first recovery mode is selected in the case of a sheet jam in the first image forming mode, and the second recovery mode is selected in the case of a sheet jam in the second image forming mode. That is, the recovering mode corresponding to the image forming mode before a sheet jam is selected.
In the above-described image forming apparatus, since the first recovering mode or the second recovering mode is selected in accordance with the image forming mode before a sheet jam after the sheet jam has occurred, the productivity of the entire system will be in some cases reduced depending on the number of copies or the number of originals.
In order to overcome this problem, images may be formed always in the first recovering mode. However, recycling operations of originals will increase the possibility of damage to the originals, the occurrence of a sheet jam, and even rupture of originals.